Multiuser detection is extended to distributed scenarios. Each cooperating receiver makes preliminary decisions on the received bits of multiple users based on its own observations. Then the preliminary decisions are combined at the fusion center to produce the nal decision. Optimum schemes, consisting of a fusion rule and the corresponding receiver decision rules, are found for various criteri...

We study the performance and capacity of a quasi-synchronous code division multiple access (QS-CDMA) cellular system employing the decorrelating detector. It is assumed that each of N users has a GPS generated local clock, and attempts to transmit in synchrony with the other users in its cell. The detector makes use of the small timing uncertainties to build the interference signal space and pe...

A new linear multiuser detector that directly minimizes the bit-error rate (BER) subject to a set of reasonable constraints is proposed. It is shown that the constrained BER cost function has a unique global minimum. This allows us to develop an efficient barrier Newton method for finding the coefficients of the proposed detector using information about timing, amplitudes, channels, and the sig...

I n this paper, a two-stage adaptive minimum meansquared error (MMSE) detector for synchronous DS-CDMA system is considered in a Rayleigh fading channel. The near-far effect causes performance degradation of a DS-CDMA system. To improve performance of the adaptive MMSE detector in a nearfar environment, a near-far resistant decorrelating decisionfeedback detector (DDFD) is combined with the ada...

A new and efficient class of nonlinear receivers is introduced for digital communication systems. These “iterated-decision” receivers use optimized multipass algorithms to successively cancel interference from a block of received data and generate symbol decisions whose reliability increases monotonically with each iteration. Two variants of such receivers are discussed: the iterated-decision e...

A systematic approach to decision feedback multiuser detection is introduced for the joint detection of symbols of K simultaneously transmitting users of a synchronous correlated waveform multiple-access (CWMA) channel with Gaussian noise. A new performance criterion called symmetric energy is defined which is a low-noise indicator of the joint error rate that at least one user is detected erro...

Chaos based communications have drawn increasing attention over the past years. Chaotic signals are derived from non-linear dynamic systems. They are aperiodic, broadband and deterministic signals that appear random in the time domain. Because of these properties, chaotic signals have been proposed to generate spreading sequences for wide-band secure communication recently. Like conventional DS...

In direct-sequence code-division multiple-access systems, impulsive noise leads to increased bit error rates and hence limits the performance. The main novel contribution of this paper is the improvement achieved on the decorrelating detector by the addition of a nonlinear clipper in order to eliminate impulsive components. The system is studied under multi-path fading with impulsive noise. It ...

Abstract — Consider a code-division multipleaccess system in a correlated Rayleigh fading environment in which the fading gains are independent among the users but correlated among the receive diversity branches, and which uses the decorrelating multiuser detector. The branches are combined using maximal-ratio combining, which requires channel estimation. The channel is estimated by means of pi...